Moving from private arrangement to Child Maintenance Service: problems and issues in a complex situation

Hi Everyone - your help and advice here is very much appreciated.

My ex-wife and I (we divorced in 2016) have had a private agreement regarding shared expenses for our 3 children (22, 19 and 14) since 2019. She and I negotiated this between ourselves with some difficulty, as communication between us is hard. At the time our now 22yr old, and our 14yr old, lived with me 6 nights out of 14, and with her the rest of the time. Our now 19yr old lived with me continuously as she threw him out of her house in 2019, and he has refused to go back to hers since then. Despite me suggesting to him many, many times that he go back to live under her roof, he has never returned and is now at university, returning to me during holidays.

I asked her for some money in 2019 towards his upkeep as he was with me full time but she refused, saying that "she doesn't see it like that", and knowing that she was very upset about the situation, I did not pursue it. She has never paid me anything towards his upkeep all the time he has lived with me.

The private agreement that we made says explicitly that no maintenance is to be paid by either parent, and it details shared expenses and separate expenses. As far as I was concerned, this was the agreement that we were operating, and I was doing so in good faith. It is unsigned, and retitled by her as a "Statement of Intentions", but it has stood since then.

Now that the two older children have left home, my ex has written via her lawyer saying that the private agreement "no longer works" and she is making a maintenance demand for having our daughter 2 days more each fortnight (1 day per week) than me. She's made some assumptions on the calculations, but the figure is around £560 per month.

I simply do not have this. One of the complications of my life is that my now-partner and I (we have been together since 2016) tried to bring her daughter to live with us (she lives in a different city), but we failed (our court costs were around £100,000 in the end) and we had to sell our shared house both to fund these costs, and to buy two separate flats in the two cities to house her daughter in the one, and my daughter in the other. We travel week-about between the two (a journey of 3hrs each way) in order for us to stay together. In order to purchase the two flats last year, I under-reported my expenses for the freelance portion of my income, and have since last year had both a huge tax bill and two mortgages to pay each month (one of them is part-paid by my now partner, but the expense is considerable). The tax bill will be paid off by the end of this calendar year, but the mortgages will remain.

My ex-wife consistently refuses to discuss co-parenting issues to any real extent - we have a solicitor-brokered and signed agreement since 2018 that says that we must have monthly co-parenting meetings, but when I have contacted her to arrange these she refuses to answer - and she has frequently signed our daughter up for things that I cannot afford, and has come seeking for money after she has done so rather than discussing whether or not we can share these costs. Co-parenting with her is extremely difficult, and we find common ground on very little even when we do manage to discuss things (mostly via text, email - or now via her lawyer).

She also undertook legal proceedings in 2020/21 to force me to sign so that our daughter could go to the same (private, fee-paying) secondary school as our two elder children. At the time, our daughter was showing clear signs of an eating disorder (something that my ex and her side of the family suffer from) and I was very very unhappy about her going to such a high-pressure (both socially and academically) environment without the support of the large group of friends who she had made at primary school - friends who she would not have at the secondary school (over 3 years now her eating disorder has become progressively worse, and my daughter has struggled under the social pressure, just as I feared). I was prepared to allow for our daughter to go halfway through secondary school, once she was more settled, as our sons had, but my ex would not accept this.

To make things more complex, our separation (and then divorce) agreement was 75/25 in my ex's favour, as the one thing she asked me on divorce was for me not to take her house from her, and I honoured that by not going for 50/50. She also could not raise the money to pay me the 25% she owed me in full, so I agreed that she could pay me the remainder when our daughter turned 21. This was a substantial amount (almost a third of the total), linked to the value of her house. In order to pay for our second son to go to private school, I allowed her to draw on this (i.e. reduce the amount she owed me), as I do not have the capital or disposable income to do so. I paid for our first son to go from the capital that she did give me on divorce. I would have been happy for her to do the same (i.e reduce the amount she owed me) to allow our daughter to go too, but the amount remaining would not cover the whole period - and I was, in truth, so upset at the lack of discussion around schools, and the dismissal of our daughter's eating disorder issues, that I agreed, but on the condition that she paid all of the fees and expenses related to our daughter's school. I have since had to borrow money from my parents against the amount that she still owes me in order to fund the deposit for one of the flats we had to buy following the court order keeping my partners' and my daughters in separate cities, so that money is effectively now all gone.

It's a complicated situation. At the root of it is my shock at being asked to pay maintenance suddenly, when we have a private agreement that states that no maintenance will be paid either way, dating from 2019 - and also that she paid no maintenance for our son to live with me (following her throwing him out of her house) for a period of 4 years, but is now demanding that I pay for the 1 extra day a week that our daughter stays with her. I am quite prepared to pay my share of things that we agree for our daughter  in advance, when I have the money - but most things are arranged without consultation by her, so I am always in the position of being unable to pay, or saying that I can't.

I'd appreciate some advice here. I feel very strongly that I should not be paying maintenance, when she did not for a child that lived with me for years full-time, and we agreed jointly that no maintenance was to be payable then or in the future; additionally her refusal to have monthly co-parenting meetings with me (in contravention of our signed legal agreement) contributes significantly to this very unhappy situation. I can no longer afford to use a lawyer (for all of the reasons above) but she sends missives through hers on a regular basis, and takes our daughter on trips abroad on a regular basis. What happens if I ignore the demand? Is there some solid basis on which I can argue against it? If I refused to pay, will it end up in court? If so, I would have to defend myself. What are the bases for reducing the amount I am asked to pay? If I do pay, do I still need to contribute to shared expenses, or is that the total I am liable for in the eyes of the law?

For clarity, I live in Scotland, and I'm aware it's a slightly different system (and government agency) from the rest of the country.

Thank you all!

J